Have you ever had a large number of windows and applications open on your Windows desktop, and you’d really like to hide them all to get back to your clean desktop? You can do that with a Windows shortcut… Windows Key + D.
In my example, I had 10 applications open on my Windows desktop, and I really wanted to get back to a clean Windows desktop. However, I really didn’t want to shut down each application. I used the Windows Key + D shortcut, and all my open windows became hidden, giving me a clean Windows desktop:

Even nicer… I can use the Windows Key + D shortcut again, and all my hidden windows will reappear!